Spark gap protection in cathode ray tube sockets

ABSTRACT

A cathode ray tube socket with capability for separately grounding the high voltage pin on the one hand, and the remainder of the pins on the other, in the event of a voltage excess in the pins. Separate grounding prevents a spark from jumping from the high voltage pin to ground and then back to one of the remaining pins, thus damaging the tube. The socket comprises an insulating support and a plurality of metal contacts mounted therein and adapted to conductively receive the tube pins. Included within the support are electrically and physically separate first and second grounding plates. The first grounding plate is spaced from the contact associated with the high voltage pin and the second grounding plate is spaced from the contacts associated with the remaining pins. Means are also provided for independently electrically connecting each of the grounding plates to ground such that sparks can bridge the gap between the respective grounding plates and the contacts associated therewith without affecting the other contacts so as to damage the tube.

United States Patent 1191 Pittman 1451 Feb. 11, 1975 [75] lnventor:

[73] Assignee: Industrial Electronic Hardware Corp., New York, NY.

221 Filed: Aug. 1, 1973 21 Appl. No.: 384,701

[52] US. Cl. 339/14 T, 339/111, 339/194R, 313/325, 328/8, 317/6l.5 [51] Int. Cl H0lr 3/06 [58] Field of Search 339/14, 111, 112, 193, 339/194, 176 MP, 143; 313/325; 328/8; 317/6l.5

[56] References Cited UNITED STATES PATENTS 3,377,612 4/1968 Klier et a1. 339/143 T 3,587,029 6/1971 Knowles 339/176 MP X 3,603,914 9/1972 Manetti et a1 339/143 T 3,643,201 2/1972 Harwood 339/177 R X 3,683,228 8/1972 Kleen 339/193 P X 3,733,522 5/1973 Simouits et a1 339/143 T X 3,771,098 ll/l973 Dempsey 33 /l4 R Robert B. Pittman, River Edge, NJ. I

Primary ExaminerRoy D. Frazier Assistant Examiner-Robert A. Hafer [57}- ABSTRACT A cathode ray tube socket with capability for separately grounding the high voltage pin on the one hand, and the remainder of the pins on the other, in the event of a voltage excess in the pins. Separate grounding prevents a spark from jumping from the high voltage pinto ground and then back to one of the remaining pins, thus damaging the tube. The socket comprises an insulating support and a plurality of metal contacts mounted therein and adapted to conductively receive the tube pins. Included within the support are electrically and physically separate first and second grounding plates. The first grounding plate is spaced from the contact associated with the high voltage pin and the second grounding platev is spaced from the contacts associated with the remaining pins. Means are also provided for independently electrically connecting each of the grounding plates to ground such that sparks can bridge the gap between the respective grounding plates and the contacts associated therewith without affecting the other contacts so as to damage the tube.

23 Claims, 8 Drawing Figures I PATENTED H281 Hers sum 3 0F 5 SPARK GAP PROTECTION IN CATHODE RAY TUBE SOCKETS This invention relates to cathode ray tube sockets, and more particularly to a cathode ray tube socket provided with separate grounding means to prevent a spark which has jumped to ground from the high voltage pin from jumping back to one of the other pins and damaging the tube.

Cathode ray tubes arepresently in wide use in the electronics industry. Although they perform a variety of functions, these tubes are probably most well known for their use as picture tubes in television receivers. As is common with most tubes, cathode ray tubes have a plurality of pins or leads extending from the base of the tube to enable the tube to be plugged into a socket and thus connected to the remainder of the electrical component. These leads or pins are usually arranged in a ring-like configuration. The normal operating potential of all of the pins or leads, except one, is in the range of a few thousand volts. However, the remaining pin, often referred to as the high voltage pin, operates at a substantially higher potential, usually in the neighborhood of 25,000 volts DC. or greater.

ln order to prevent damage to the cathode ray tube caused by excessive voltage at the pins, cathode ray tube sockets are normally provided with sometype of safety device in the form of a grounding apparatus. Usually, the grounding apparatus permits a spark to jump from the pin contact to ground, in the event that the pin is operating at an excessive potential. This prevents damage to the tube due to excessive potential at one of the pins by providing a non-destructive path to eliminate the excess.

In the past, the grounding apparatus has commonly taken the form of a single grounding plate which is spaced from the pin terminalsin the socket by means of an insulating plate. The insulating plate is provided with holes aligned with the pin terminals to permit the spark to jump from the terminal to the grounding plate. The distance between the grounding plate and the terminal will determine the potential necessary to permit a spark to bridge the gap between the terminal and the grounding plate. Because of the normal operating range of the high voltage pin, the space between the high voltage pin terminal and the grounding plate is usually greater than the space between the remaining pin terminals and the grounding plate so that a higher potential is necessary before a spark can bridge the gap between the high voltage pin terminal and the grounding plate. However, this grounding configuration has a very great disadvantage. Specifically, if a spark jumps from the high voltage pin terminal to the ground plate, the potential of the ground plate may rise faster than it can be dissipated to ground. A second spark may then jump from the ground plate back to one of the other pin terminals thus seriously damaging the tube.

It is, therefore, the prime object of the present invention to provide a cathode ray tube socket having separate and independent grounding capability such that a spark which has jumped from the high voltage pin terminal to ground cannot jump back to any of the other pin terminals and thus damage the tube.

It is another object of the present invention to provide a cathode ray tube socket with separate and independent grounding capability which is approximately the same size as conventional grounding sockets and which can be easily and inexpensively manufactured.

In accordance with the present invention, a cathode ray tube socket is provided having an insulating support comprising a front plate and a rear plate which are assembled to produce the body of the socket. The front plate is provided with a plurality of axially'situated apertures in a ring-like configuration corresponding to the position of the pins or leads which extend from the base of the cathode ray tube. In each of these apertures is situated a metal terminal. The terminal is connectedv to a wire which runs to the appropriate portion of the electronic component.

Interposed between the front and rear plates of the insulating support is an insulating plate and two separate grounding plates. The insulating plate has apertures therein each of which is aligned with a different one of the terminals. Interposed between the insulating plate and the rear plate of the insulating support is the low voltage grounding plate. This grounding plate is connected by means of a wire to a ground, such as the chassis of the electrical component and is utilized to ground all of the pins, with the exception of the high voltage pin, in the event of a voltage excess thereon.

A second grounding plate which is physically and electrically independent of the low voltage grounding plate is utilized to ground the high voltage pin. In the first embodiment of the present invention, the high voltage grounding plate is mounted on two protrusions extending axially from the interior wall of the front plate of the insulating support. This grounding plate is therefore spaced from and in a different plane than the low voltage grounding plate. In this embodiment the high voltage grounding plate is axially displaced from the high voltage terminal and therefore the spark jumping from the high voltage terminal to the high voltage grounding plate will jump in a direction which is parallel to the axis of the cathode ray tube.

In the second embodiment, the high voltage grounding plate is mounted directly on the rear plate of the insulating support in the same plane as the low voltage grounding plate but radially offset from the high voltage terminal. In this embodiment, a spark jumping from the high voltage terminal to the high voltage grounding plate will jump in a plane perpendicular to the axis of the tube.

The high voltage grounding plate in each of the embodiments has a separate grounding wire extending therefrom to an appropriate grounding member, such as the chassis of the electrical component, and is physically and electrically separated from the low voltage grounding plate. In this way, a spark which has jumped from the high voltage terminal to the high voltage grounding plate cannot jump back to any of the remaining contacts to damage the tube.

To the accomplishment of the above and to such other aspects as may hereinafter appear, the present invention relates to the cathode ray tube socket as defined in the appended claims and as described in the specification, taken together with the accompanying drawings, wherein like numerals refer to like parts and in which:

FIG. 1 is a front elevational view of the first preferred embodiment of the present invention;

FIG. 2 is an isometric exploded view of the first preferred embodiment of the present invention;

FIG. 3 is a front elevational view of the interior face of the rear plate of the first preferred embodiment of the present invention;

FIG. 4 is a cross-sectional view of the first preferred embodiment of the present invention;

FIG. 5 is an isometric view of the high voltage grounding plate of the first preferred embodiment of the present invention;

FIG. 6 is an isometric view of a pin terminal of the first preferred embodiment of the present invention;

FIG. 7 is an isometric exploded view of a second preferred embodiment of the present invention; and

FIG. 8 is a front view of the second preferred embodiment of the present invention with the front plate removed.

The cathode ray tube socket of the present invention comprises an insulating support, which is made up of a front plate, generally designated A, and a rear plate, generally designated B, which, when assembled form the insulating body of the socket. The front plate A has, on the surface thereof, a plurality of axially extending apertures, generally designated C. In each of the apertures C is situated a terminal generally designated D, which may take the form of a pin gripping member. Each terminal D is connected to a separate wire which extends from the socket to the appropriate location in the electrical component thus connecting the component to the tube.

lnterposed between the front plate A and the rear plate B of the insulating support is an insulating plate, generally designated E, and two grounding plates, generally designated F and G, respectively. Insulating plate E serves tp space grounding plate F from the low voltage terminals D, and has a plurality of apertures therein each one of which is aligned with a different one of the low voltage terminals D. The grounding plate F, situated between insulating plate E and rear plate B, is utilized to ground all of the pins with the exception of the high voltage pin. Plate F is connected to a wire which leads to a ground element.

In the first embodiment of the present invention grounding plate G, which is utilized to ground the high voltage pin, is situated on a pair of protrusions which extend axially from the interior surface of front plate A. Therefore, in this embodiment, plate G is in a plane parallel to but spaced from the plane of the high voltage terminal D. The spark which will jump from the high voltage terminal to plate G will, therefore, jump in a direction which is parallel to the axis of the tube. Plate G is independently and separately connected to ground. In the second embodiment, plate G is mounted directly to the interior wall of rear plate B and therefore is situated substantially in the same plane as ground plate F and high voltage terminal D. However, plate G is radially offset from the high voltage terminal along a plane perpendicular to the axis of the tube such that the spark will travel perpendicular to the axis of the tube.

Referring now to FIG. 2, each of the plates A and B which assemble to form the support is composed of a molded insulated material and is generally of disc shape. Plate A is provided with a plurality of apertures C which extend through the plate and are situated in a ring configuration, each aperture aligned with the corresponding pin on the base of the cathode ray tube.

Each terminal D preferably takes the form of a pin gripping member 10 and a wire clamping member 13 connected thereto. Pin gripping members 10 (FIG. 6) are situated in apertures C and designed to make electrical contact with the corresponding pins of the tube. Wire clamping members 13 are situated in channels 11 one of which radially extends from each aperture C. Each member 13 clamps a wire 14 which is connected to the appropriate location in the electrical component.

Plates A and B each have an extended portion on the top thereof. The terminal Dwhich is associated with the high voltage pin is situated in the extended portion to provide extra insulation for this terminal. The high voltage terminal D is connected to a wire 15 which extends out the extended portion of plate A.

Insulating plate E, which is interposed between plates A and B is made of a thin insulating material and is preferably of ring shape with the portion aligned with the extended portion of plates A and B removed. A plurality of apertures 12 are formed through plate E each of which is aligned with one of the terminals D. Apertures 12 will permit a spark to jump between the terminalD and the grounding plate F which is situated on the other side of plate E from terminal D. Plate E serves to space the grounding plate from the terminals.

In each embodiment, two separate and independent grounding plates F and G are provided, one for grounding the terminals associated with low voltage pins and the other for the terminal associated with the high voltage pin. The low voltage grounding plate F is substantially the same size and shape as insulating plate E except that it has a means 16, which may take the form of a wire wrap terminal or wire clamping member, to permit the plate to be connected to a ground wire 25. Plate F is sandwiched between insulating plate E and rear plate B such that sparks travel parallel to the axis of the tube when they bridge the gap between the terminals D and plate F.

In the first embodiment, as shown in FIGS. 1-6, plate A is provided with a pair of rod-like protrusions 19 which extend axially from the interior surface thereof. On the ends of protrusions 19 are situated pins 21 which extend through apertures 23 on grounding plate G to mount the plate to the protrusions. Protrusions l9 serve to axially space plate G, which is parallel to the plane of plate A, from the interior surface thereof (See FIG. 4). The terminal D associated with the high voltage pin is placed in aperture C in plate A immediately adjacent plate G and between protrusions 19. Therefore, a spark bridging the gap between the high voltage terminal and plate G will travel parallel to the axis of the tube.

Enclosure 22 is provided to cover an aperture through the surface of plate B aligned with plate G to allow for the extra room necessary because of the spacing of plate G from the surface of plate A. Enclosure 22 is also made of insulating material to insulate plate G from the environment. Means 30 are provided to connect a wire (not shown) to plate G for grounding purposes. These means may take the form of a wire clamping member 29 (FIG. 5) or a wire wrap terminal (FIGS. 1 and 2). This grounding wire is separate and independent from ground wire 25.

In the second embodiment of the present invention, as shown in FIGS. 7 and 9, plate G takes the form of an elongated member fastened directly to the interior surface of plate B and hence in the same plane as plate F. Plate G is radially offset from the high voltage terminal D thus providing the necessary spacing between the plate and the terminal. Hence, a spark bridging the gap between the high voltage terminal and plate G in this embodiment will travel perpendicular to the axis of the tube. No enclosure'22 is necessary on this embodiment because gap spacing is provided radially instead of axially. Plate G is connected to a ground wire (not shown) by a means 30 on the outer end of plate G. Means 30 may take the form of a wire wrap terminal or a wire clamping member, for example. A

In both embodiments the interior surface of rear plate B is provided with a protruding U-shaped insulating ridge 24 which extends into a U-shaped groove 26 opposing it on the interior surface of front plate A. ln the first embodiment, insulating ridge 24 is interrupted to provide clearance for plate G to pass into enclosure 22 but otherwise surrounds the area in which high voltage is present on three sides. In the second embodiment insulating ridge 24 is interrupted only on one side thereof to provide a path for the spark to jump from the high voltage terminal D to grounding plate G situated immediately along side insulating ridge 24.

A plurality of protrusions 28 extend axially from the interior surface of rear plate B in the second embodiment and the interior surface of front plate A in the first embodiment. These protrusions 28 will pass through indentations 17 along the periphery of grounding plate F and insulating plate E and be mounted in apertures 33 in the interior surface of the opposite plate to assemble the socket. Indentations 17 along the periphery of grounding plate F and insulating plate E not only provide clearance for protrusions 28 but also serve the additional function of retaining each of these plates in the proper position with respect to the remainder of the socket.

Two preferred embodiments of the present invention have been specifically disclosed herein for purposes of illustration. lt is apparent that many modifications and variations may be made upon the specific structures disclosed herein. It is intended to cover all of these variations and modifications which fall within the scope of this invention as defined by the appended claims.

I claim:

1. A tube socket for use with a tube having a first pin normally operating in a first potential range and a second pin normally operating in a second potential range, said socket comprising a support, first and second terminals mounted on said support and adapted to conductively receive said first and second pins respectively, first and second grounding means on said support, said first mounting means being spaced from said first terminal to form a gap therebetween and said second grounding means being spaced from said second terminal to form a gap therebetween, means for independently electrically connecting each of said grounding means to ground, whereby a spark can independently bridge said gap between the respective means and the terminal associated therewith without affecting the order terminal.

2. The socket according to claim 1 wherein said first grounding means comprises a first electrically conductive member and said second grounding means comprises a second electrically conductive member, said first and second members being electrically isolated from each other.

3. The socket according to claim 2 wherein said first member and said second member are situated in substantially the same plane.

4. The socket according to claim 3 wherein the tube has a longitudinal axis and wherein said plane is substantially perpendicular to said axis.

5. The socket according to claim 3 wherein said first grounding member is radially offset from said first terminal such that a spark from said terminal travels in a direction substantially perpendicular to the axis of the tube.

6. The socket according to claim 2 wherein said first member and said second member are axially spaced from each other and therefore situated in first and second planes.

7. The socket according to claim 6 wherein said first and second planes are both substantially perpendicular to the axis of the tube.

8. The socket according to claim 2 wherein said first grounding member and said first terminal are axially offset from each other such that a spark from said first terminal travels in a plane substantially parallel to the axis of the tube.

9. The socket according to claim 1 wherein said pins are situated in a ring and said terminals substantially define a ring interrupted by spacing between said terminals.

10. A tube socket for use with a cathode ray tube of the type having a high voltage pin and a plurality of other pins spaced apart in a ring configuration, said socket comprising a support, a plurality of terminals mounted on said support each of which is adapted to conductively receive a different one of said pins, first and secnd grounding members, said first grounding member being spaced from the terminal associated with the high voltage pin and said second member being spaced from the remainder of the terminals, and means for independently electrically connecting each of said grounding means to ground whereby a spark can independently bridge the gap between the respective members and the terminals associated therewith without affecting the other terminals.

11. The socket according to claim 10 wherein said first grounding member comprises a first electrically conductive plate and said second grounding member comprises a second electrically conductive plate, said first and second plates being electrically isolated from each other.

12. The socket according to claim 10 wherein said first member and said second member are situated in substantially the same plane.

13. The socket according to claim 12 wherein said plane is substantially perpendicular to the axis of the tube.

14. The socket according to claim 12 wherein said first grounding member is radially offset from said first terminal such that a spark from said terminal travels in a direction substantially perpendicular to the axis of the tube.

15. The socket according to claim 10 wherein said first member and said second member are axially spaced from each other and therefore situated in first and second planes.

16. The socket according to claim 15 wherein said first and second planes are both substantially perpendicular to the axis of the tube.

17. The socket according to claim 10 wherein said first grounding member and said first terminal are axially offset from each other such that a spark from said first terminal travels in a plane substantially parallel to the axis of the tube.

18. The socket according to claim 10 wherein said pins are situated in a ring and said terminals substantially define a ring interrupted by spacing between said terminals.

19. The socket according to claim 10 further comprising a pair of axially extending projections mounted on said support and means for mounting said first member on said projections.

20. The socket according to claim 19 wherein said means for mounting comprises a pin extending from each of said projections and a pair of apertures on said first member, said pins being insertable into said apertures.

21. The socket according to claim 20 wherein said first terminal is situated betwen said projections.

22. The socket according to claim 19 wherein said support further comprises a cover for said projections and said first member mounted thereon.

23. The socket according to claim 10 wherein said support comprises a first insulating plate and a second insulating plate, a pair of projections extending from the surface of said first insulating plate, means for mounting said first member on said projections, an aperture on said second insulating plate through which said projections and said first member extend and a cover mounted over said aperture on said second insulating plate to insulate said first member. 

1. A tube socket for use with a tube having a first pin normally operating in a first potential range and a second pin normally operating in a second potential range, said socket comprising a support, first and second terminals mounted on said support and adapted to conductively receive said first and second pins respectively, first and second grounding means on said support, said first mounting means being spaced from said first terminal to form a gap therebetween and said second grounding means being spaced from said second terminal to form a gap therebetween, means for independently electrically connecting each of said grounding means to ground, whereby a spark can independently bridge said gap between the respective means and the terminal associated therewith without affecting the order terminal.
 2. The socket according to claim 1 wherein said first grounding means comprises a first electrically conductive member and said second grounding means comprises a second electrically conductive member, said first and second members being electrically isolated from each other.
 3. The socket according to claim 2 wherein said first member and said second member are situated in substantially the same plane.
 4. The socket according to claim 3 wherein the tube has a longitudinal axis and wherein said plane is substantially perpendicular to said axis.
 5. The socket according to claim 3 wherein said first grounding member is radially offset from said first terminal such that a spark from said terminal travels in a direction substantially perpendicular to the axis of the tube.
 6. The socket according to claim 2 wherein said first member and said second member are axially spaced from each other and therefore situated in first and second planes.
 7. The socket according to claim 6 wherein said first and second planes are both substantially perpendicular to the axis of the tube.
 8. The socket according to claim 2 wherein said first grounding member and said first terminal are axially offset from each other such that a spark from said first terminal travels in a plane substantially parallel to the axis of the tube.
 9. The socket according to claim 1 wherein said pins are situated in a ring and said terminals substantially define a ring interrupted by spacing between said terminals.
 10. A tube socket for use with a cathode ray tube of the type having a high voltage pin and a plurality of other pins spaced apart in a ring configuration, said socket comprising a support, a plurality of terminals mounted on said support each of which is adapted to conductively receive a different one of said pins, first and secnd grounding members, said first grounding member being spaced from the terminal associated with the high voltage pin and said second member being spaced from the remainder of the terminals, and means for independently electrically connecting each of said grounding means to ground whereby a spark can independently bridge the gap between the respective members and the terminals associated therewith without affecting the other terminals.
 11. The socket according to claim 10 wherein said first grounding member comprises a first electrically conductive plate and said second grounding member comprises a second electrically conductive plate, said first and second plates being electrically isolated from each other.
 12. The socket according to claim 10 wherein said first member and said second member are situated in substantially the same plane.
 13. The socket according to claim 12 wherein said plane is substantially perpendicular to the axis of the tube.
 14. The socket according to claim 12 wherein said first grounding member is radially offset from said first terminal such that a spark from said terminal travels in a direction substantially perpendicular to the axis of the tube.
 15. The socket according to claim 10 wherein said first member and said second member are axially spaced from each other and therefore situated in first and second planes.
 16. The socket according to claim 15 wherein said first and second planes are both substantially perpendicular to the axis of the tube.
 17. The socket according to claim 10 wherein said first grounding member and said first terminal are axially offset from each other such that a spark from said first terminal travels in a plane substantially parallel to the axis of the tube.
 18. The socket according to claim 10 wherein said pins are situated in a ring and said terminals substantially define a ring interrupted by spacing between said terminals.
 19. The socket according to claim 10 further comprising a pair of axially extending projections mounted on said support and means for mounting said first member on said projections.
 20. The socket according to claim 19 wherein said means for mounting comprises a pin extending from each of said projections and a pair of apertures on said first member, said pins being insertable into said apertures.
 21. The socket according to claim 20 wherein said first terminal is situated betwen said projections.
 22. The socket according to claim 19 wherein said support further comprises a cover for said projections and said first member mounted thereon.
 23. The socket according to claim 10 wherein said support comprises a first insulating plate and a second insulating plate, a pair of projections extending from the surface of said first insulating plate, means for mounting said first member on said projections, an aperture on said second insulating plate through which said projections and said first member extend and a cover mounted over said aperture on said second insulating plate to insulate said first member. 